1. Field of the Invention
The present invention relates to a navigation apparatus.
2. Description of the Related Art
In recent years, navigation apparatus for use on board vehicles have been developed and commercialized. These apparatus operate on the following principles: A number of strategic points in given geographical areas are coded in number to form road maps. The maps are stored in a recording medium such as a CD-ROM for use with the navigation apparatus on board the vehicle. The onboard apparatus recognizes the current location of the vehicle using outputs from its distance and direction sensors, while reading from memory groups of road map data applicable to the area in which the vehicle is currently located. The appropriate area map is displayed on a display device, automatically showing the current position of the vehicle.
This kind of prior art navigation apparatus is constructed to display the current vehicle location relative to the appropriate road map data. This requires installing a mass storage medium in which to store road map data and a high-resolution display device on which to display area maps. Also needed are sophisticated computations to be carried out for such applications as plotting of maps and estimation of the current location. These requirements have amounted to construction of the conventional navigation apparatus, few of which are small in size or low in cost. While the exact current position of the vehicle can be known with the apparatus displaying the position relative to the appropriate road map data, some users may find such display containing too much information. It sometimes takes only a limited amount of information about the current vehicle position for most vehicle drivers to reach their destinations.